1. Field of the Invention
The present invention relates to a machine for liquid treatment of fabrics in rope form forming a closed loop of the type that uses a reduced ratio of the treatment bath.
2. Description of the Prior Art
Machines of this type are already known comprising an impregnation device for the rope fabric with a treatment bath, a movable mechanical conveyor device with adjustable speed and being provided with a perforated supporting surface for the fabric, said surface being located above the level of the treatment bath which is contained in a lower vat, means for transferring the fabric from the impregnation device to the mechanical conveyor, and placing the fabric thereon so that pleats are formed, and a reel for guiding the fabric from the outlet of the mechanical conveyor to the inlet of said impregnation device.
In the German patent document Nos. 2,439,747 and 2,531,528 are described machines of this type wherein the rope mechanical conveyor is a linear conveyor having a conveyor rectilinear section and between the outlet and the inlet of this conveyor, the fabric is guided by a horizontally extending pipe having a length almost equal to that of the mechanical conveyor. Inside said pipe, the fabric is impregnated by the treatment liquid and at the same time the fabric is advanced through the inside of the pipe by the action of the liquid itself which is pressure-fed into the pipe through an annular nozzle, i.e. the fabric advance along said pipe is made by the transportation system called "jet".
Jasper & Co. GmbH's German Pat. No. 2,620,387 discloses a machine wherein the rope of fabric mechanical conveyor is provided with a perforated circular platform rotatively fitted above a fixed vat containing the treatment bath. In this machine, the fabric rope advance is also performed by the "jet" system i.e. by the action of the treatment liquid pressure in the impregnation device and also comprises an impregnation and guide pipe of the fabric rope which is circularly curved or wound above the circular conveyor and also comprises a reel for guiding the fabric from the conveyor to the dragging and impregnation device but said reel has not been designed to carry out the fabric advance.
All these machines have the disadvantage that with the fabric driving "jet" system used, the pressure injected liquid exerts a strong dragging action against the fabric which can then be damaged, particularly when short staple woven fabrics are dealt with. Also in these known machines it is very difficult to coordinate the speed transferred to the fabric by the liquid action with the speed at which the fabric is carried by means of the mechanical conveyor, so that it is easy for pilings or stresses to be produced in the fabric before or after its passage through the impregnation device.